JP5723127B2 - COMPOUND FOR ORGANIC EL ELEMENT AND ORGANIC EL ELEMENT - Google Patents

Description

  The present invention relates to a compound for an organic EL device and an organic EL device.

  An organic compound having an anthracene structure is a very effective compound as a high-efficiency and long-life organic EL host material, and is particularly known to be excellent as a host material for a blue light-emitting element (for example, Patent Document 1). ~ 4). Among them, by using an organic compound having a dianthracene structure including two or more anthracene structures as an organic EL host material, it is possible to produce an organic EL element particularly excellent in reliability and light emission efficiency (patent) Reference 5).

International Publication No. 2004/01587 Special table 2008-530086 JP 2005-515233 A JP 2005-531552 A JP-A-8-12600

  However, the organic compound having a dianthracene structure described in Patent Document 5 and the like is likely to be crystallized during the production of the device, and there is a concern about the effect on the device life due to the formation of microcrystals. Also tended to be expensive. In addition, there is room for improvement in driving life.

  The present invention has been made in view of the above circumstances, and when used as a constituent material of an organic EL element, the process temperature during the production of the organic EL element can be lowered, and sufficient light emission luminance and It aims at providing the compound for organic EL elements from which a drive life is obtained, and the organic EL element using this compound.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by using a compound represented by the following general formula (1) in an organic EL device. The present invention provides a compound for an organic EL device represented by the following general formula (1).

（式中、Ｘ^１ａ、Ｘ^２ａ、Ｘ^１ｂ、Ｘ^２ｂ、Ｘ^３ｂ、Ｘ^１ｃ、Ｘ^２ｃ及びＸ^３ｃは、それぞれ独立に、水素原子、置換基を有していてもよいアリール基、又は、置換基を有していてもよい芳香族複素環式基を示す。）で表される基、又は、置換基を有していてもよい二価の芳香族複素環を示す。 Here, in the formula (1), R ¹ , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ and R ²⁰ each independently have a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent. An aralkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, a heterocyclic group which may have a substituent, or a substituent; Represents an aromatic heterocyclic group which may have, L represents a single bond, an alkylene group, a divalent group containing an aromatic hydrocarbon skeleton, an oxygen atom, a sulfur atom, a formula:

( ^Wherein , X ^1a , X ^2a , X ^1b , X ^2b , X ^3b , X ^1c , X ^2c and X ^3c are each independently a hydrogen atom, an aryl group which may have a substituent, or Represents an aromatic heterocyclic group which may have a substituent.) Or a divalent aromatic heterocyclic ring which may have a substituent.

  According to such a compound for an organic EL element, when used as a constituent material of the organic EL element, the process temperature at the time of producing the organic EL element can be lowered, and sufficient light emission luminance and driving life can be obtained. . The reason why such an effect can be obtained by the compound for an organic EL device of the present invention is not necessarily clear, but the present inventors consider as follows.

  That is, the compound for an organic EL device of the present invention has a dianthracene structure in which the 2-position of one anthracene structure and the 9-position of the other anthracene structure are bonded to each other through the linking group L. Thereby, since the symmetry of the whole molecule | numerator is falling with the positional relationship of two anthracene structures, it is thought that crystallinity falls.

  Moreover, in order to reduce the symmetry of the compound, it is usually necessary to introduce a large substituent, but in this case, there is a problem that the sublimation temperature of the compound becomes high. On the other hand, in the organic EL device compound of the present invention, the symmetry of the whole molecule is lowered due to the positional relationship between the two anthracene structures, so there is no need to introduce a large substituent to lower the symmetry. . Therefore, a simple substituent such as a phenyl group having high emission efficiency and a low molecular weight can be introduced as the substituent. Thereby, since the molecular weight of a compound can be made small, it is thought that the process temperature at the time of preparation of an organic EL element can be reduced.

In the compound for an organic EL device of the present invention, R ⁹ , R ¹⁰ and R ²⁰ are each independently a substituent in the above formula (1) because the stability and luminous efficiency of the compound can be improved. It is preferably an aryl group which may have an aromatic group or an aromatic heterocyclic group which may have a substituent.

  Moreover, this invention is an organic EL element provided with 1 or 2 or more organic layers between two electrodes arrange | positioned facing each other, Comprising: At least 1 layer of this organic layer is said organic EL element The organic EL element containing the compound for use is provided. According to this organic EL element, since the compound for organic EL element of the present invention is included, sufficient emission luminance and driving life can be obtained.

  Moreover, this invention is provided with 1 or 2 or more organic layers between the two electrodes arrange | positioned facing each other, At least 1 layer of the organic layers contains said organic EL element compound. Provided is a method for producing an organic EL device comprising a coating step of applying a solution obtained by dissolving the compound for organic EL device in a solvent onto an electrode or a layer formed on the electrode. To do. Since the compound for an organic EL device has high solubility in a solvent, it can be sufficiently used as a material applied on the electrode or a layer formed on the electrode as a solution. Even when at least one of the organic layers is formed by such a coating process, the obtained organic EL element can obtain sufficient light emission luminance and driving life.

  According to the present invention, when used as a constituent material of an organic EL element, the process temperature in the production of the organic EL element can be lowered, and a compound for an organic EL element capable of obtaining sufficient light emission luminance and driving life, and An organic EL device using this compound can be provided. Moreover, the compound for organic EL elements which has the dianthracene structure of this invention is easy to refine | purify because it is easy to melt | dissolve in a solvent compared with the compound which has the conventional dianthracene structure, and its sublimation temperature is low. Furthermore, since the compound for organic EL elements of the present invention has high solubility in a solvent, an organic EL element can also be produced by a coating method.

It is a schematic cross section which shows the organic EL element which concerns on 1st Embodiment of this invention. It is a schematic cross section which shows the organic EL element which concerns on 2nd Embodiment of this invention. It is a graph which shows the relationship between the molecular weight of a compound which has a dianthracene structure, and sublimation purification temperature.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

(Compound for organic EL device)
The compound for organic EL devices according to a preferred embodiment of the present invention is a compound having a dianthracene structure represented by the general formula (1).

In the general formula (1), ^{R n} groups (n = 1,3~18,20) may be "optionally substituted alkyl group". The “alkyl group” moiety may be linear or branched, and the carbon number thereof is preferably 1 to 12, more preferably 1 to 6, and still more preferably 1 to 3. Suitable alkyl groups include methyl, ethyl and propyl groups, with methyl being particularly preferred. These “alkyl groups” may be further substituted with a substituent such as a methoxy group or an ethoxy group, but an alkyl group having no substituent is also suitable.

The R ⁿ group (n = 1, 3-18, 20) may also be an “aryl group optionally having a substituent”. Specific examples of the “aryl group” moiety include a phenyl group, a biphenylyl group, a terphenylyl group, a naphthyl group, and a pyrenyl group. More specifically, the following chemical formulas (i-1) to (i-17) are used. And the group represented. These groups may be further substituted with a substituent such as a methyl group, an ethyl group, a methoxy group, or a cyclohexyl group.

The R ⁿ group (n = 1, 3-18, 20) may also be an “aralkyl group optionally having a substituent”. Specific examples of the “aralkyl group” include a benzyl group and a naphthylmethyl group. These groups may be further substituted with a substituent such as a methyl group, an ethyl group, a methoxy group, or a cyclohexyl group.

The R ⁿ group (n = 1, 3-18, 20) may also be an “alkoxy group optionally having a substituent”. Specific examples of the “alkoxy group” moiety include a methoxy group, an ethoxy group, a propyloxy group, and a tert-butoxy group. These groups may be further substituted with a substituent such as a methoxy group or an ethoxy group, but an alkoxy group having no substituent is also suitable.

The R ⁿ group (n = 1, 3-18, 20) may also be an “aryloxy group optionally having substituent (s)”. Specific examples of the “aryloxy group” moiety include a phenoxy group and a naphthyloxy group. These groups may be further substituted with a substituent such as a methyl group, an ethyl group, a methoxy group, or a cyclohexyl group.

The R ⁿ group (n = 1, 3-18, 20) may also be a “heterocyclic group optionally having a substituent”. Specific examples of the “heterocyclic group” moiety include a piperidinyl group, a pyrrolidinyl group, a tetrahydrofuranyl group, and a tetrahydrothienyl group. More specifically, the following chemical formulas (ii-1) to (ii-11) The group represented by these is mentioned. These groups may be further substituted with a substituent such as a methyl group, an ethyl group, a methoxy group, a cyclohexyl group, or a pyridyl group.

The R ⁿ group (n = 1, 3-18, 20) may also be an “aromatic heterocyclic group optionally having a substituent”. Specific examples of the “aromatic heterocyclic group” moiety include a pyridyl group, a pyrimidinyl group, a triazinyl group, a furanyl group, a thienyl group, and an indolyl group. In more detail, the following chemical formula (ii-12) Group represented by-(ii-26) is mentioned. These groups may be further substituted with a substituent such as a methyl group, an ethyl group, a methoxy group, a cyclohexyl group, or a pyridyl group.

R ⁿ group (n = 1, 3-18, 20) is preferably a hydrogen atom, an aryl group which may have a substituent, or an aromatic heterocyclic group which may have a substituent, A hydrogen atom and an optionally substituted phenyl group are more preferred. Among R ⁿ groups (n = 1, 3-18, ²⁰ ), R ⁹ , R ¹⁰ , and R ²⁰ are preferably groups other than hydrogen atoms. R ⁹ , R ¹⁰ and R ²⁰ are more preferably an aryl group which may have a substituent or an aromatic heterocyclic group which may have a substituent, and may have a substituent. More preferred are a phenyl group, a naphthyl group, a pyridyl group or a thienyl group.

  In general formula (1), L may be an “alkylene group”. 1-12 are preferable, as for carbon number of this "alkylene group", 1-6 are more preferable, and 1-3 are still more preferable. Suitable alkylene groups include a methylene group, an ethylene group and a propylene group, with a methylene group being particularly preferred.

  L may also be a “divalent group containing an aromatic hydrocarbon skeleton”. Specific examples of the “divalent group containing an aromatic hydrocarbon skeleton” include a phenylene group, a naphthylene group, an anthrylene group, and a pyrenylene group. More specifically, the following chemical formulas (iii-1) to ( (iii-27) (the two bonds in these groups may each be bonded to the 9-position of one anthracene structure in formula (1), and the other anthracene structure It may be bonded to position 2. Hereinafter, the same applies to a group having two bonds.) In these groups, some of the hydrogen atoms on the aromatic hydrocarbon skeleton may be substituted with a substituent such as a methyl group, an ethyl group, a methoxy group, a cyclohexyl group, or a phenyl group.

  L may also be an oxygen atom or a sulfur atom, or a divalent group represented by the following chemical formula.

  The divalent group is preferably a divalent group represented by the following chemical formulas (iv-1) to (iv-7).

In the above formula, X ^1a , X ^2a , X ^1b , X ^2b , X ^3b , X ^1c , X ^2c , X ^3c and X ^4c may each independently have a hydrogen atom or a substituent. An aryl group or an aromatic heterocyclic group which may have a substituent is shown. Preferred examples of these include a hydrogen atom, a phenyl group, a naphthyl group, and a pyridyl group. These groups may be further substituted with a substituent such as a methyl group, an ethyl group, a methoxy group, or a cyclohexyl group.

  L may also be a “divalent aromatic heterocyclic ring optionally having a substituent”. Specific examples of the “divalent aromatic heterocycle” moiety include a pyridinediyl group, a pyrrolediyl group, and a quinolinediyl group. More specifically, the following chemical formulas (v-1) to (v-20) are used. And the group represented. In these groups, a hydrogen atom on the divalent aromatic heterocyclic ring may be further substituted with a substituent such as a methyl group, an ethyl group, a methoxy group, or a cyclohexyl group.

  L is preferably a single bond, a divalent group containing an aromatic hydrocarbon skeleton, or a divalent aromatic heterocyclic ring which may have a substituent, a single bond, a phenylene group, a biphenylene group, a naphthylene group, An anthrylene group, a pyridinediyl group or a thiophenediyl group is more preferred.

  The above-mentioned compound for an organic EL device preferably has a molecular weight of 800 or less, more preferably 700 or less, from the viewpoint that the process temperature can be further lowered.

(Specific examples of compounds for organic EL devices)
Preferable examples of the compound for an organic EL device of the present invention include compounds represented by the following general formulas (I) to (VII), which are represented by the general formulas (I), (II), and (VI). Are preferred. Specific examples of these compounds include the following formulas (I-1) to (I-19), (II-1) to (II-19), (III-1) to (III-19), (IV- 1) to (IV-19), (V-1) to (V-19), (VI-1) to (VI-19), (VII-1) to (VII-12), (VIII-1) To (VIII-3), (IX-1) to (IX-3), and compounds represented by (X-1) to (X-18).

（式中、Ｒ^９、Ｒ^１０及びＲ^２０は、それぞれ独立に、式（１）におけるものと同様の置換基を示し、Ｌ^ａは、上記（ｉｉｉ−１）〜（ｉｉｉ−２７）、（ｉｖ−１）〜（ｉｖ−７）、（ｖ−１）〜（ｖ−２０）で表される基等を示す。）

^(Wherein, R ^{9, R 10} and ^{R 20} each independently represent the same substituent as in Formula (1), ^{L a} is the (iii-1) ~ (iii -27), ( (iv-1) to (iv-7), and groups represented by (v-1) to (v-20) are shown.)

(Method for producing compound for organic EL device)
The production method of the compound (1) for organic EL devices will be described by taking the following compounds (11a), (12a) and (15a) as examples.

  The compound (11a) in which L is a single bond can be produced as follows.

The compound represented by the following general formula (B) is obtained by reacting the following compound (A) with organolithium R ⁹ Li and then with organolithium R ¹⁰ Li. A compound represented by the following general formula (C) is obtained by allowing potassium iodide and sodium phosphinate monohydrate to act on the compound (B). Separately, triethyl borate is allowed to act on the compound (D) obtained by introducing R ²⁰ by a known method to obtain a compound represented by the following general formula (E). Compound (11a) is obtained by reacting compound (C) with compound (E) in the presence of tetrakistriphenylphosphine palladium.

  The compound (12a) in which L is a divalent organic group can be produced as follows.

  The compound represented by the following general formula (F) is obtained by allowing triethyl borate to act on the compound (C) obtained by the above reaction. Apart from this, Br-L-Br is allowed to act on the compound (E) obtained by the above reaction to obtain a compound represented by the following general formula (G). Compound (12a) is obtained by reacting compound (F) with compound (G) in the presence of tetrakistriphenylphosphine palladium.

The compound (15a) in which L has a nitrogen atom and the nitrogen atom is directly bonded to the anthracene structure can be produced as follows. The compound (15a) corresponds to the compound in which L is a divalent group represented by the above (iv-3) and X ^4c is a hydrogen atom.

An aniline is allowed to act on the compound (H) obtained by introducing R ²⁰ by a known method to obtain a compound represented by the following general formula (J). Compound (15a) is obtained by reacting compound (C) and compound (J) obtained by the above reaction in the presence of tetrakistriphenylphosphine palladium.

In the above manufacturing method, as a method of introducing a specific group other than a hydrogen atom as ^{R n} groups of compound for organic EL device (1) (n = 1,3~8,11~18) , for example, advance the A method using a compound having such a group as a raw material, or after synthesizing a compound in which R ⁿ groups (n = 1, 3-8, 11-18) are hydrogen atoms, these groups are introduced by a known reaction. There is a way to do it.

(Organic EL device)
FIG. 1 is a schematic cross-sectional view showing a first embodiment of an organic EL element according to the present invention. An organic EL element 100 shown in FIG. 1 has a structure in which a light emitting layer 10 is sandwiched between two electrodes (a first electrode 1 and a second electrode 2) arranged to face each other.

  FIG. 2 is a schematic cross-sectional view showing a second embodiment of the organic EL element according to the present invention. The organic EL element 200 shown in FIG. 2 includes a hole injection layer 14, a hole transport layer 11, a light emitting layer 10, and two electrodes (a first electrode 1 and a second electrode 2) arranged to face each other. The electron injection / transport layer 13 is sandwiched. The hole injection layer 14, the hole transport layer 11, the light emitting layer 10, and the electron injection transport layer 13 are all organic layers, and are stacked in this order from the first electrode 1 side. The electron injecting and transporting layer 13 may be an inorganic layer (metal layer, metal compound layer, etc.) (the same applies hereinafter).

  In the first and second embodiments, the first electrode 1 is formed on the substrate 4, but the stacking order from the substrate 4 side may be reversed. That is, in the case of the organic EL element of the second embodiment, the second electrode 2, the electron injection transport layer 13, the light emitting layer 10, the hole transport layer 11, the hole injection layer 14, and the first electrode 1 from the substrate 4 side. They may be stacked in order.

  Moreover, the organic EL device compound of the present invention may be contained in any of the organic layers described above, but is preferably contained in the light emitting layer.

  In the above embodiment, the first electrode 1 and the second electrode 2 function as a hole injection electrode (anode) and an electron injection electrode (cathode), respectively. While holes (holes) are injected and electrons are injected from the second electrode 2, the organic EL element compound in the light emitting layer emits light based on these recombination.

  Moreover, the suitable thickness of the light emitting layer 10, the electron injection transport layer 13, the hole injection layer 14, and the hole transport layer 11 is all 1-200 nm.

(substrate)
The substrate 4 can be used without particular limitation as long as it is provided in a conventional organic EL element, and is an amorphous substrate such as glass or quartz, Si, GaAs, ZnSe, ZnS, GaP, A crystal substrate such as InP or a metal substrate such as Mo, Al, Pt, Ir, Au, Pd, or SUS can be used. Further, a thin film made of a crystalline or amorphous ceramic, metal, organic substance or the like formed on a predetermined substrate may be used.

  When the substrate 4 side is the light extraction side, it is preferable to use a transparent substrate such as glass or quartz as the substrate 4, and it is particularly preferable to use an inexpensive glass transparent substrate. The transparent substrate may be provided with a color filter film, a color conversion film containing a fluorescent material, a dielectric reflection film, or the like for adjusting the color light.

(First electrode)
The first electrode 1 functions as a hole injection electrode (anode). Therefore, the material of the first electrode 1 is not particularly limited as long as it is provided in the conventional organic EL element, but it can be efficiently applied to a layer adjacent to the first electrode 1 and A material that can uniformly apply an electric field is preferable.

  When the substrate 4 side is the light extraction side, the transmittance at a wavelength of 400 to 700 nm, which is the emission wavelength region of the organic EL element, particularly the transmittance of the first electrode 1 at the wavelength of each RGB color is 50% or more. Preferably, it is 80% or more, more preferably 90% or more. When the transmittance of the first electrode 1 is less than 50%, the light emission from the light emitting layer 10 is attenuated, and it is difficult to obtain the luminance necessary for image display.

The 1st electrode 1 with comparatively high light transmittance can be comprised using the transparent conductive film comprised with various oxides. As such a material, indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), zinc oxide (ZnO), tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), and the like are preferable. It is particularly preferable in that a thin film having a uniform in-plane specific resistance can be easily obtained.

  The film thickness of the first electrode 1 is preferably determined in consideration of the above-described light transmittance. For example, when using an oxide transparent conductive film, the film thickness is preferably 10 to 500 nm, more preferably 30 to 300 nm. When the film thickness of the first electrode 1 exceeds 500 nm, the light transmittance may be insufficient and the first electrode 1 may be peeled off from the substrate 4 in some cases. Further, although the light transmittance is improved as the film thickness is decreased, when the film thickness is less than 10 nm, the resistivity is increased and the driving voltage of the organic EL element tends to be increased.

(Second electrode)
The second electrode 2 functions as an electron injection electrode (cathode). The material of the second electrode 2 is not particularly limited as long as it is provided in a conventional organic EL element, and examples thereof include a metal material, an organometallic complex, or a metal compound. It is preferable to use a material having a relatively low work function so that electrons can be efficiently and reliably injected into the substrate 10 and may be transparent.

  Specific examples of the metal material constituting the second electrode 2 include alkali metals such as Li, Na, K or Cs, alkaline earth metals such as Mg, Ca, Sr or Ba, or Al (aluminum). . Alternatively, a metal having properties similar to those of an alkali metal or alkaline earth metal such as La, Ce, Sn, Zn, or Zr can be used. Furthermore, oxides or halides of the above metal materials can also be used. Further, it may be a mixture or alloy containing the above materials, and a plurality of these may be laminated.

  The film thickness of the second electrode 2 only needs to be such that electrons can be uniformly injected, and may be 0.1 nm or more.

  An auxiliary electrode may be provided on the second electrode 2. Thereby, the electron injection efficiency to the light emitting layer 10 grade | etc., Can be improved, and the penetration | invasion of the water | moisture content or the organic solvent to the light emitting layer 10 or the electron injection transport layer 13 can be prevented. As a material for the auxiliary electrode, a general metal can be used because there is no restriction on work function and charge injection capability. However, it is preferable to use a metal having high conductivity and easy handling. In particular, in the case where the second electrode 2 includes an organic material, it is preferable to select appropriately according to the type and adhesion of the organic material.

  Examples of the material used for the auxiliary electrode include Al, Ag, In, Ti, Cu, Au, Mo, W, Pt, Pd, and Ni. Among them, when a low-resistance metal such as Al and Ag is used, electrons are used. The injection efficiency can be further increased. Moreover, higher sealing properties can be obtained by using a metal compound such as TiN. These materials may be used alone or in combination of two or more. Moreover, when using 2 or more types of metals, you may use as an alloy. Such an auxiliary electrode can be formed by, for example, a vacuum deposition method or the like.

(Hole injection layer)
For the hole injection layer, arylamine, phthalocyanine, polyaniline / organic acid, polythiophene / polymer acid, or the like can be used.

(Hall transport layer)
For the hole transport layer, any of hole transport materials such as low molecular materials and polymer materials can be used. Examples of the hole transporting low molecular weight material include pyrazoline derivatives, arylamine derivatives, stilbene derivatives, and triphenyldiamine derivatives. Also, hole transporting polymer materials include polyvinyl carbazole (PVK), polyethylenedioxythiophene (PEDOT), polyethylenedioxythiophene / polystyrene sulfonic acid copolymer (PEDOT / PSS), polyaniline / polystyrene sulfonic acid copolymer. (Pani / PSS) and the like. One of these hole transport materials may be used alone, or two or more thereof may be used in combination.

  The hole injection layer and the hole transport layer may be formed as a hole injection transport layer using the same material.

(Light emitting layer)
In the light emitting layer 10, it is preferable to use the above compound (1) as a constituent material as a host material. According to the organic EL element including such a light emitting layer 10, a sufficiently high light emission luminance and a sufficiently long luminance half life can be obtained.

  In addition, as a dopant material when the above compound (1) is used as a host material, aromatic hydrocarbon compounds such as organometallic complex compounds, naphthalene, anthracene, naphthacene, perylene, benzofluoranthene, naphthofluoranthene, etc. And their derivatives, such as aromatic amino compounds, further styrylamine or tetraaryldiamine derivatives, or quinacridone, coumarin, 4- (di-cyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H -Pyran (DCM) and their derivatives are preferred. Although suitable content of dopant material changes with combinations of host material and dopant material, it is preferable that it is 0.1-30 mass% on the basis of the whole constituent material of a light emitting layer, and it is 1-10 mass% Is more preferable.

(Electron injection transport layer)
As a material for the electron injecting and transporting layer 13, it is preferable to use the compound for organic EL elements (1) of the present invention. An organic EL device including the electron injecting and transporting layer 13 containing such a material can have sufficiently high emission luminance and sufficiently long luminance half life as compared with a conventional organic EL device.

  The electron injecting and transporting layer 13 may use the compound (1) alone as a constituent material, contains the compound (1) as a main component material, and is further used as a material for a conventional electron injecting and transporting layer. You may contain the 1 type (s) or 2 or more types. Examples of such materials include oxadiazole derivatives, imidazopyridine derivatives, anthraquinodimethane and its derivatives, benzoquinone and its derivatives, naphthoquinone and its derivatives, anthraquinone and its derivatives, tetracyanoanthraquinodimethane and its derivatives. , Fluorene and derivatives thereof, diphenyldicyanoethylene and derivatives thereof, phenanthroline and derivatives thereof, and low molecular materials such as metal complexes having these compounds as ligands, and polymer materials such as polyquinoxaline and polyquinoline.

  The electron injecting and transporting layer 13 may be a substantially two-layered layer in which the compound (1) is vapor-deposited on the light emitting layer side and another material is vapor-deposited thereon.

  The organic EL device according to this embodiment can be manufactured by a known manufacturing method except that the light emitting layer 10 contains the compound for organic EL device of the present invention. As a method for forming each organic layer including such a light emitting layer 10, a vacuum vapor deposition method, an ionized vapor deposition method, a coating method, or the like can be appropriately selected and employed depending on the material constituting the organic layer.

  Specific examples of the coating method include a method in which a material used for the organic layer is dissolved in a solvent, and then applied by a conventionally known method such as a spin coating method, and the solvent is removed from the coating solution by vacuum drying or the like. . Examples of the solvent used in this coating method include aromatic hydrocarbon solvents such as toluene.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  Hereinafter, the contents of the present invention will be described more specifically with reference to examples and comparative examples. In addition, this invention is not limited to the following Example.

<Synthesis Example 1>
The following compound (11) was synthesized by the following method. The reaction formula is shown below.

(Synthesis of 2-bromo-9,10-diphenylanthracene (1b))
5.32 g (18.5 mmol) of 2-bromoanthraquinone was suspended in a mixed solvent of 30 ml of dehydrated toluene and 30 ml of dehydrated diethyl ether under argon. After cooling to −20 ° C., 21 ml (39.9 mmol) of a 1.9 mol / l phenyllithium butyl ether solution was added and reacted for 12 hours. After adding pure water to stop the reaction, the solvent was removed from the organic layer extracted by liquid separation to obtain a mixture of diol (1a).

  To this mixture, 30.5 g (185 mmol) of potassium iodide, 32 g (305 mmol) of sodium phosphinate monohydrate and 100 ml of acetic acid as a solvent were added and refluxed for 12 hours. The precipitated substance was filtered and purified by column chromatography to obtain 4.9 g (12 mmol) of 2-bromo-9,10-diphenylanthracene (1b). The yield was 64.8%.

(Synthesis of 10-phenylanthracene-9-boronic acid (1c))
5.2 g (15.6 mmol) of 9-bromo-10-phenylanthracene was dissolved in 60 ml of dehydrated THF under argon. After cooling to −40 ° C., 10.4 ml (17.2 mmol) of a 1.65 mol / l butyllithium normal hexane solution was added and reacted for 1 hour. Next, 2.5 g (17.2 mmol) of triethyl borate was added and reacted for 2 hours, and then 20 ml of 1N hydrochloric acid was added to complete the reaction. After removing the solvent from the organic layer extracted by liquid separation, 3.4 g (11.4 mmol) of 10-phenylanthracene-9-boronic acid (1c) was obtained by recrystallization. The yield was 73.1%.

(Synthesis of Compound (11))
1.64 g (4 mmol) of 2-bromo-9,10-diphenylanthracene (1b) synthesized by the above reaction under argon, 1.2 g (4 mmol) of 10-phenylanthracene-9-boronic acid (1c), As a catalyst, 120 mg of tetrakistriphenylphosphine palladium was dissolved in a mixed solvent of 60 ml of toluene and 20 ml of ethanol. Subsequently, 30 ml of 2M sodium carbonate aqueous solution was added, and it reacted at 100 degreeC for 12 hours. After cooling to room temperature, the precipitate was collected and purified by column chromatography to obtain 1.9 g (3.26 mmol) of pale yellow crystals (11). The yield was 81.5%. This compound (11) was analyzed by mass spectrum and NMR, and was identified as the desired product.

<Synthesis Example 2>
The following compound (12) was synthesized by the following method. The reaction formula is shown below.

(Synthesis of 9,10-diphenylanthracene-2-boronic acid (2a))
4.68 g (11.4 mmol) of 2-bromo-9,10-diphenylanthracene (1b) synthesized in Synthesis Example 1 was dissolved in 60 ml of dehydrated THF under argon. After cooling to −40 ° C., 7.6 ml (12.5 mmol) of a 1.65 mol / l butyllithium normal hexane solution was added and reacted for 1 hour. Subsequently, 1.83 g (12.5 mmol) of triethyl borate was added and reacted for 2 hours, and then 20 ml of 1N hydrochloric acid was added to complete the reaction. After removing the solvent from the organic layer extracted by liquid separation, 3.07 g (8.2 mmol) of 9,10-diphenylanthracene-2-boronic acid (2a) was obtained by recrystallization. The yield was 72%.

(Synthesis of 9- (4-bromophenyl) -10-phenylanthracene (2b))
2.46 g (8.26 mmol) of 10-phenylanthracene-9-boronic acid (1c) synthesized in Synthesis Example 1 and 3.9 g (16.5 mmol) of dibromobenzene, and 250 mg of tetrakistriphenylphosphine palladium as a catalyst, Was dissolved in a mixed solvent of 80 ml of toluene and 25 ml of ethanol. Subsequently, 40 ml of 2M sodium carbonate aqueous solution was added and reacted at 100 ° C. for 12 hours. Extraction of the compound in the organic layer by liquid separation and purification by column chromatography were performed to obtain 2 g (4.9 mmol) of 9- (4-bromophenyl) -10-phenylanthracene (2b). The yield was 59.3%.

(Synthesis of Compound (12))
9,10-diphenylanthracene-2-boronic acid (2a) 1.35 g (3.62 mmol) synthesized in the above reaction under argon and 9- (4-bromophenyl) -10-phenylanthracene (2b) 1 0.5 g (3.67 mmol) and 120 mg of tetrakistriphenylphosphine palladium as a catalyst were dissolved in a mixed solvent of 60 ml of toluene and 20 ml of ethanol. Subsequently, 30 ml of 2M sodium carbonate aqueous solution was added, and it reacted at 100 degreeC for 12 hours. After cooling to room temperature, the precipitate was collected and purified by column chromatography to obtain 1.77 g (2.69 mmol) of pale yellow crystals (12). The yield was 74.3%. This compound (12) was analyzed by mass spectrum and NMR, and was identified as the desired product.

<Synthesis Example 3>
The following compound (13) was synthesized by the following method. The reaction formula is shown below.

(Synthesis of 9- (4′-bromobiphenyl-4-yl) -10-phenylanthracene (3a))
2.98 g (10 mmol) of 10-phenylanthracene-9-boronic acid (1c) and 6.24 g (20 mmol) of 4,4′-dibromobiphenyl synthesized in Synthesis Example 1, and 300 mg of tetrakistriphenylphosphine palladium as a catalyst. Were dissolved in a mixed solvent of 80 ml of toluene and 25 ml of ethanol. Subsequently, 40 ml of 2M sodium carbonate aqueous solution was added and reacted at 100 ° C. for 12 hours. Extraction of the compound in the organic layer by liquid separation and purification by column chromatography were carried out to obtain 1.6 g (3.3 mmol) of 9- (4′-bromobiphenyl-4-yl) -10-phenylanthracene (3a). Obtained. The yield was 33%.

(Synthesis of Compound (13))
1.3 g (3.5 mmol) of 9,10-diphenylanthracene-2-boronic acid (2a) synthesized in Synthesis Example 2 under argon and 9- (4′-bromobiphenyl-4-) synthesized by the above reaction Yl) -10-phenylanthracene (3a) 1.6 g (3.3 mmol) and tetrakistriphenylphosphine palladium 100 mg as a catalyst were dissolved in a mixed solvent of toluene 60 ml and ethanol 20 ml. Subsequently, 30 ml of 2M sodium carbonate aqueous solution was added, and it reacted at 100 degreeC for 12 hours. After cooling to room temperature, the precipitate was collected and purified by column chromatography to obtain 1.9 g (2.59 mmol) of pale yellow crystals (13). The yield was 78.4%. This compound (13) was analyzed by mass spectrum and NMR, and was identified as the desired product.

<Synthesis Example 4>
The following compound (14) was synthesized by the following method. The reaction formula is shown below.

(Synthesis of 9- (4- (4-bromo-diphenylamino) phenyl) -10-phenylanthracene (4a))
1.82 g (6.1 mmol) of 10-phenylanthracene-9-boronic acid (1c) and 5 g (12.4 mmol) of 4,4′-dibromotriphenylamine synthesized in Synthesis Example 1, and tetrakistri as a catalyst. 200 mg of phenylphosphine palladium was dissolved in a mixed solvent of 80 ml of toluene and 25 ml of ethanol. Subsequently, 40 ml of 2M sodium carbonate aqueous solution was added and reacted at 100 ° C. for 12 hours. Extraction of the compound in the organic layer by liquid separation and purification by column chromatography were performed, and 1.6 g (2.8 mmol) of 9- (4- (4-bromo-diphenylamino) phenyl) -10-phenylanthracene (4a ) The yield was 45.5%.

(Synthesis of Compound (14))
1.05 g (2.8 mmol) of 9,10-diphenylanthracene-2-boronic acid (1b) synthesized in Synthesis Example 1 under argon and 9- (4- (4-bromo-diphenylamino) phenyl) -10 -1.6 g (2.8 mmol) of phenylanthracene (4a) and 100 mg of tetrakistriphenylphosphine palladium as a catalyst were dissolved in a mixed solvent of 60 ml of toluene and 20 ml of ethanol. Subsequently, 30 ml of 2M sodium carbonate aqueous solution was added, and it reacted at 100 degreeC for 12 hours. After cooling to room temperature, the precipitate was collected and purified by column chromatography to obtain 1.3 g (1.57 mmol) of pale yellow crystals (14). The yield was 56.1%. This compound (14) was analyzed by mass spectrum and identified as the desired product.

<Synthesis Example 5>
The following compound (15) was synthesized by the following method. The reaction formula is shown below.

(Synthesis of 9-phenylamino-10-phenylanthracene (5a))
5 g (13.2 mmol) of 9-iodo-10-phenylanthracene, 3.72 g (40 mmol) of aniline, 3.6 g (26 mmol) of potassium carbonate, and a catalytic amount of Cu were heated to 200 ° C. by flowing an argon gas. For 12 hours. After cooling to room temperature, toluene is added and insoluble matter is filtered, and then the compound in the organic layer is separated by liquid separation and purified by column chromatography, and 2.3 g (6.7 mmol) of 9-phenylamino-10- Phenylanthracene (5a) was obtained. The yield was 50.8%.

(Synthesis of Compound (15))
1.1 g (2.7 mmol) of 2-bromo-9,10-diphenylanthracene (1b) synthesized in Synthesis Example 1 under argon, and 0.9 g of 9-phenylamino-10-phenylanthracene (5a) (2. 6 mmol), 100 mg of tetrakistriphenylphosphine palladium, 125 mg of tert-butylphosphine, and 1 g of tert-butoxypotassium were dissolved in 40 ml of xylene and reacted at 150 ° C. for 12 hours. Extraction of the compound in the organic layer by liquid separation and purification by column chromatography were performed to obtain 1.5 g (2.2 mmol) of pale yellow crystals (15). The yield was 84.6%. This compound (15) was analyzed by mass spectrum and identified as the desired product.

<Measurement of sublimation purification temperature>
Sublimation purification of the compound for an organic EL device was performed using a train sublimation method. Along with this, the temperature at which all 1 g samples sublime in 5 to 10 hours was set as the set temperature, and the sublimation purification temperature was determined as the average value of the two results. Compounds (11) to (13) in which the dianthracene structures synthesized in Synthesis Examples 1 to 3 are bonded to each other at the 2-position and the 9-position (molecular weights are 582, 658, and 734, respectively) and molecular weights similar to those compounds. Sublimation purification temperatures were measured for known compounds (but the following (21) to (24), molecular weights 506, 658, 734, and 834, respectively) having a dianthracene structure but not bonded to each other at the 2-position and the 9-position. The results are shown in a graph with the molecular weight on the horizontal axis and the sublimation purification temperature on the vertical axis (see FIG. 3). According to FIG. 3, it is recognized that the sublimation purification temperature is clearly lower in the compound group of the present invention than in the control compound group. Compounds (21) and (22) are known compounds used in Comparative Examples 1 and 2 below, respectively.

<Example 1>
An ITO transparent electrode thin film having a thickness of 100 nm was formed on a glass substrate by RF sputtering and patterned. This glass substrate with an ITO transparent electrode was subjected to ultrasonic cleaning using a neutral detergent, acetone and ethanol, and then pulled up from boiling ethanol and dried. After the surface of the transparent electrode was washed with UV / O _3, it was fixed to a substrate holder of a vacuum deposition apparatus, and the inside of the tank was depressurized to 1 × 10 ⁻⁴ Pa or less.

  Next, while maintaining the reduced pressure state, N, N′-diphenyl-N, N′-bis [N- (4-methylphenyl) -N-phenyl- (4-aminophenyl)]-1, which has the following structure, 1′-biphenyl-4,4′-diamine (31) was deposited to a thickness of 50 nm at a deposition rate of 0.1 nm / sec to form a hole injection layer.

  Next, N, N, N ′, N′-tetrakis (m-biphenyl) -1,1′-biphenyl-4,4′-diamine (32) having the following structure is 10 nm at a deposition rate of 0.1 nm / sec. A hole transport layer was formed by vapor deposition.

  Further, while maintaining the reduced pressure, the compound (11) and the compound (33) having the following structure as a dopant were mixed at a mass ratio of 98: 2 with a total deposition rate of 0.1 nm / sec to a thickness of 40 nm. The light emitting layer was formed by vapor deposition.

  Next, while maintaining the reduced pressure state, the compound (11) was successively deposited to a thickness of 20 nm at a deposition rate of 0.1 nm / sec, and Alq3 was successively deposited to a thickness of 5 nm at a deposition rate of 0.1 nm / sec. An injection transport layer was obtained.

  Next, LiF was deposited at a deposition rate of 0.1 nm / sec to a thickness of 0.5 nm, used as an electron injection electrode, Al was deposited as a protective electrode to 100 nm, and finally sealed with glass to obtain an organic EL device. The sublimation purification of the compound (11) can be performed at any stage as long as it is before vapor deposition.

When a DC voltage was applied to this organic EL element, blue-green light emission with a current efficiency of 10.7 cd / A was confirmed at an initial current density of 10 mA / cm ² . Subsequently, when a continuous driving test was performed at an initial luminance of 5000 cd / m ² , the luminance half life was 540 h.

<Example 2>
An organic EL device was produced in the same manner as in Example 1 except that the compound (12) was used instead of the compound (11) in Example 1. When a DC voltage was applied to this organic EL element, blue-green light emission with a current efficiency of 11.3 cd / A was confirmed at an initial current density of 10 mA / cm ² . Subsequently, when a continuous driving test was performed at an initial luminance of 5000 cd / m ² , the luminance half life was 660 h.

<Example 3>
An organic EL device was produced in the same manner as in Example 1 except that the compound (13) was used instead of the compound (11) in Example 1. When a DC voltage was applied to the organic EL element, blue-green light emission with a current efficiency of 11.8 cd / A was confirmed at an initial current density of 10 mA / cm ² . Subsequently, when a continuous driving test was performed at an initial luminance of 5000 cd / m ² , the luminance half life was 720 h.

<Comparative Example 1>
An organic EL device was produced in the same manner as in Example 1 except that the following compound (21) was used instead of the compound (11) in Example 1.

When a DC voltage was applied to the organic EL element, blue-green light emission with a current density of 10.1 cd / A was confirmed at an initial current density of 10 mA / cm ² . Subsequently, when a continuous driving test was performed at an initial luminance of 5000 cd / m ² , the luminance half life was 380 h.

<Comparative Example 2>
An organic EL device was produced in the same manner as in Example 1 except that the following compound (22) was used instead of the compound (11) in Example 1.

When a direct current voltage was applied to the organic EL element, blue-green light emission with a current efficiency of 11.5 cd / A was confirmed at an initial current density of 10 mA / cm ² . Subsequently, when a continuous driving test was performed at an initial luminance of 5000 cd / m ² , the luminance half life was 460 h.

  According to Examples 1 to 3 and Comparative Examples 1 and 2, the organic EL device in which the compound (11), (12) or (13) is included in the organic layer includes the compound (21) or (22) in the organic layer. It has been shown that it exhibits higher characteristics than the organic EL element obtained.

<Example 4>
An ITO transparent electrode thin film having a thickness of 100 nm was formed on a glass substrate by RF sputtering and patterned. This glass substrate with an ITO transparent electrode was subjected to ultrasonic cleaning using a neutral detergent, acetone and ethanol, and then pulled up from boiling ethanol and dried. Next, the surface of the transparent electrode was washed with UV / O ₃ and used for production of the organic EL device shown below.

  A polyethylenedioxythiophene / polystyrene sulfonic acid (PEDOT / PSS) film having a thickness of 60 nm is formed on the substrate on which the ITO transparent electrode thin film has been formed by spin coating, followed by vacuum drying at 80 ° C. An injection transport layer was obtained.

  Next, the compound (11) and the compound (33) as a dopant were mixed at a mass ratio of 98: 2. This mixture was prepared using a toluene solvent so as to have a concentration of 2% by mass to obtain a coating solution.

  Using the coating solution, a film having a thickness of 40 nm was formed by spin coating on the hole injecting and transporting layer in which PEDOT / PSS was formed, and vacuum drying was performed at 80 ° C. to obtain a light emitting layer.

Next, the substrate was fixed to a substrate holder of a vacuum deposition apparatus, and the inside of the tank was depressurized to 1 × 10 ⁻⁴ Pa or less. While maintaining the reduced pressure state, Alq3 was deposited to a thickness of 5 nm at a deposition rate of 0.1 nm / sec to form an electron injecting and transporting layer.

  Next, LiF was deposited at a deposition rate of 0.1 nm / sec to a thickness of 0.5 nm, used as an electron injection electrode, Al was deposited as a protective electrode to 100 nm, and finally sealed with glass to obtain an organic EL device. The sublimation purification of the compound (11) can be performed at any stage as long as it is before vapor deposition.

When a DC voltage was applied to the organic EL element, blue-green light emission with a current efficiency of 9.2 cd / A was confirmed at an initial current density of 10 mA / cm ² . Subsequently, when a continuous driving test was performed at an initial luminance of 5000 cd / m ² , the luminance half life was 400 h.

<Example 5>
An organic EL device was produced in the same manner as in Example 4 except that the compound (12) was used instead of the compound (11) in Example 4. When a DC voltage was applied to the organic EL element, blue-green light emission with a current efficiency of 9.6 cd / A was confirmed at an initial current density of 10 mA / cm ² . Subsequently, when a continuous driving test was performed at an initial luminance of 5000 cd / m ² , the luminance half life was 480 h.

<Example 6>
An organic EL device was produced in the same manner as in Example 4 except that Compound (13) was used instead of Compound (11) in Example 4. When a DC voltage was applied to the organic EL element, blue-green light emission with a current efficiency of 9.7 cd / A was confirmed at an initial current density of 10 mA / cm ² . Subsequently, when a continuous driving test was performed at an initial luminance of 5000 cd / m ² , the luminance half life was 510 h.

<Comparative Example 3>
An organic EL device was produced in the same manner as in Example 4 except that the compound (21) was used instead of the compound (11) in Example 4. However, the mixture in which the compound (21) and the compound (33) are mixed at a mass ratio of 98: 2 does not dissolve even at a concentration of 0.5% by mass in the toluene solvent, and it is impossible to prepare a coating solution. It was.

<Comparative Example 4>
An organic EL device was tried in the same manner as in Example 4 except that the compound (22) was used instead of the compound (11) in Example 4. However, the mixture in which the compound (22) and the compound (33) are mixed at a mass ratio of 98: 2 does not dissolve even at a concentration of 0.5% by mass in the toluene solvent, and it is impossible to prepare a coating solution. It was.

  According to Examples 4 to 6 and Comparative Examples 3 to 4, the compounds (11), (12) and (13) have high solubility in solvents due to their polarities, and can be sufficiently used as coating materials. It was shown that. Moreover, although it does not reach the organic EL element (Examples 1-3) which formed all the organic layers with the vacuum evaporation method, it shows that the organic EL element of a high characteristic is also producible also by the apply | coating method. It was done.

  DESCRIPTION OF SYMBOLS 1 ... 1st electrode, 2 ... 2nd electrode, 4 ... Substrate, 10 ... Light emitting layer, 11 ... Hole transport layer, 13 ... Electron injection transport layer, 14 ... Hole injection layer, 100 ... According to 1st Embodiment Organic EL element 200 ... Organic EL element according to the second embodiment, P ... Power source.

Claims (3)

The compound for organic EL elements represented by following General formula (1).

[Wherein R ¹ , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ are Each independently having a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent; An alkoxy group which may have a substituent, an aryloxy group which may have a substituent, a heterocyclic group which may have a substituent, or an aromatic heterocyclic group which may have a substituent; Show
R ⁹ , R ¹⁰ and R ²⁰ represent a phenyl group,
L is the formula:

(In the formula, X ^1b , X ^3b , X ^2c and X ^3c are each independently a hydrogen atom, an aryl group which may have a substituent, or an aromatic heterocycle which may have a substituent. Represents a cyclic group). ] The compound for organic EL elements of Claim 1 represented by following formula (13), (14) or (15).

An organic EL device comprising one or more organic layers between two electrodes arranged opposite to each other,
At least 1 layer is an organic EL element containing the compound for organic EL elements of Claim 1 or 2 among the said organic layers.

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